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RecBCD is important for cell viability: only about 30% cells that lack RecBCD ar

ID: 213801 • Letter: R

Question

RecBCD is important for cell viability: only about 30% cells that lack RecBCD are viable. Chi sites are over-represented in the E. coli genome and are present at around 1 site/ 5 kb. Notably, the orientation of Chi sites is highly biased, with around 75% of the Chi sites oriented towards the origin of replication. What role might RecBCD and Chi most likely play in replication of damaged DNA? 4. A) Increase the frequency of clamp binding B) Degrade host proteins interfering with replication CAssist in the resumption of replication following the stalling of DNA replication fork progression. D) Increase the number of phage particles

Explanation / Answer

Answer:

RecBCD is important for cell viability, only about 30% cells that lack RecBCD are viable. Chi sites are over-represented in the E.coli genome and are present at around 1 site/5kb. Notably, the orientation of Chi sites is highly biased, with around 75% of the Chi sites oriented towards the origin of replication. What role might RecBCD and Chi most likely play in replication of damaged DNA?

A) Increase the frequency of clamp binding.

B) Degrade host proteins interfering with replication.

C) Assist in the resumption of replication following the staling of DNA replication fork progression - Correct Option (Explanation: When the replication fork stalls or breaks due to damage in DNA strand, then RecBCD exonuclease can degrade Holliday junction to reform a fork thereby allowing replisome reassembly).

D) Increase the number of phage particles